«Why do such serious automakers as Mercedes, Jaguar, Porsche, BMW still produce cars not with front drive but with rear drive? », my neighbor asked me. And really why? Let’s see.
There are Mercedes with front wheel drive such as «A» class, but this is usual thing for mini-cars like golf-class or even smaller.
The first stock car with front wheel drive was edited before World War II in 1931. This was two-cycle German DKW from Auto Union. Why didn’t it happen earlier? We can answer in such a way: it happened only when it became possible technically to make front wheels lead. All complexity was in their gear, and the case became more complicated as the whole driving moment from the engine should have been transmitted to them, or in other words, they should have pushed the car and turn simultaneously. Besides wheel rotation shouldn’t change depending on turn angle. Such half axles became to be called gears with joints of equal rate of turn. In short, as soon as these special joints were made, front wheel drive car production became more stable. There was not another way, the production with them precisely took less nerves and efforts and compared with the classical back wheel drive car production, so it was cheaper. Judge by your own – cardan isn’t necessary at all; back axle is simplified, without the gear. Power pack is portable and is easily monitored to the car.
But it is not still clear why all the mentioned above automakers did not begin to front wheel drive constructions production. The reason that these automakers produce large autos and that the largest amount of front wheel drive cars are golf-class vehicles is not a reason. It is not completely so. First, there are a lot of automakers who edit front wheel drive cars of middle class, for example, Saab, Alfa Romeo, and Volvo. Second, the U.S. produces cars de luxe supplied with V8 engine and front wheel drive, for example, Cadillac. And it is easy to do Limousine using the given platform. So, what is better front or back drive? Let’s try to understand. We will see advantages and disadvantages for each of them.
«+»of rear wheel drive
1) Engine and gear box are hang to the body with the help of soft and elastic details, so their vibration doesn’t pass to the body. It creates better comfort. There is no body vibration.
2) None jet moments pass to rudder while speeding up.
3) During start mass passes to the back and leading wheels skid less.
4) The load allocates among the axes. Besides, work allocates between front and back tires: front wheels turn and back wheels push the car forward.
«-» of rear wheel drive
1) Its production is more expensive.
2) Back wheel drive cars are heavier and they have a tunnel in the middle of the body, which lessens the saloon space.
3) Its passability is worse in sharp snow or rain.
«+» of front wheel drive
1) Its production is cheaper.
2) There is no cardan, so there is no necessity in tunnel which enhance useful place in salon.
3) A car has excellent passability.
«-» of front wheel drive
1) Vibration from the power pack and gear box pass to the body, this is a specific feature of the construction.
2) At speeding in some conditions jet moments pass to the rudder.
3) At immediate start mass passes to back but leading wheels skid more.
And what about sport front wheel drive cars? For example, VWGTI is the best model of sport car for beginners. But if we speak about powerful cars here we should quote Dr. Ferdinand Porsche’s opinion: «Real racing car must be back wheel drive and the engine should be located as close as possible to the back axle».
What wheel drive is better?
Any car engineer will answer you something like that: «with the rear wheel drive car turning front wheels make effect of stopping and back wheels — surplus power». So, back wheel drive cars are not susceptible to sliding in turn. It is called oversteer. As for front wheel drive cars, which are called cars with understeer.
«I could buy BMW or Mercedes but I drive in winter and I need the front wheel, so I have to buy Audi» as one of my friend said. And it is not only his opinion. Many drivers feel more assured if they are in front wheel drive car in winter. And it is difficult to oppose the author of the idea above. On sliding and dry surface cars with different wheel drive behave in different manners.
Let’s begin with asphalt. I’m absolutely sure that a common driver will never notice the difference between cars with front wheel drive or rear wheel drive when he drives on asphalt road. This difference appears when turnings. And here experience taken during the races helps. It allows coming to the following conclusion, unexpected for many readers: back wheel drive is better on asphalt. Evidences? If it was vice versa, bolides of Formula 1 would have front wheel drive, back wheel drive cars’ victory would be considered accidental. But today it is a norm.
Rear wheel drive car is easy to control. This can not be said about front wheel drive cars. Maybe they should be driven in different ways. Neither yes nor no. The main difference of front wheel drive car is the following: front tires make almost all work – control, speeding and the main part in braking. It is easy to overload them. As a result – tires have burnt and lost their clutch features.
Drivers of front wheel drive car should push accelerator pedal very attentively going out of turning. Immediate pushing of accelerator pedal leads to allocation of car weight, to the front part of the car loading, which causes the following: the back part becomes lighter and it leads to insufficient car turning. As a result, car is taken aside. Let’s see what racer does when he drivers front wheel drive car at high speed. He uses braking pedal with the left foot and pushes it a little coming to turning. In the middle of long turn an experienced racer throws accelerator pedal for the moment to course load allocation. It will reduce insufficient car maneuverability, and after this front tires will work better. A racer on rear wheel drive car can try to do the same, but sudden adding an accelerator pedal in the middle of steep turn causes wheels’ skidding as car turns around its axis. The car turns and at the same time begins speeding. If you do this with front wheel drive car it will be thrown out the line. A racer, driving front wheel drive car, should try to straighten the car before going out turn as quick as possible.
But let’s back to a common driver. Drivers of front wheel drive car feel more confident at winter slippery road; this is because of excellent road stability. When the way is straight and when speeding up, front wheel drive car slides less than rear wheel drive car. It is absolutely clear, that it is better to pull then to push. The front wheels pull the car after themselves, and you will never have such results with rare ones.